Oh, about five years ago I had the jaw thing. Not sure if it's the same as you. I had intense swelling and pain where I could hardly open my mouth anymore. My dentist suggested that I pry it as far as I could holding for 30 seconds, many times a day (you could use a cork to hold your mouth open). The next suggestion was the TENS machine. It took months before it felt better but I was also on a regular diet at the time.
Again, when my diet gets off I get a little tightness in my jaw. This warning gets my diet under control pretty quick as it is very uncomfortable.